Abstract: A novel force identification method is proposed for reconstructing the time history of input force from the dynamic response. The proposed scheme is based on sensitivity analysis method, where the input force is expressed as a series of parameters, and the sensitivities of dynamic response with respect to these parameters of input force are calculated in time domain, and then the sensitivities are used to update the parameters of input force iteratively in the inverse analysis. Furthermore, the inverse analysis is ill-posed, and the regularization technique is utilized to alleviate the fluctuations caused by measurement noise in dynamic response. Finally, the proposed method is successfully applied to identify the input force modeled in a generalized form of a sine series in numerical simulation.